Vox02

Yep, he is comic nerd. Whedon wrote X-Men and Runaways comics in addition to executive produce his own comics (Fray, Buffy, Angel, Firefly, Dr Horrible...). In 2001 he was ready to write and direct an Iron Man movie but declined in order to keep his TV shows. Jeph Loeb, before his tenure as head of Marvel TV, signed with Mutant Enemy (Whedon's production company) to run Buffy the Vampire Slayer animated series.

Yes. Whedon wrote an Astonishing X-Men series back in 2004-2008 (Eisner Award included) and a Runaways series back in 2007-2008. And Sugarshock (Eisner Award again). Also he wrote and/or excecutive produced his own comics: Fray (set in the Buffyverse but in the future), Buffy seasons 8-12 ( Eisner Award again), Angel, Firefly/Serenity...

Whedon did a rewrite in the first Captain America movie.